Tire identification code registration system

ABSTRACT

A tire identification code registration system for use with tire pressure detectors and a tire pressure monitoring system (TMPS) receiver. Each tire pressure detector, which includes a unique tire identification code, is coupled to a tire to detect the pressure of the tire and transmit a tire pressure signal. The receiver receives the tire pressure signal and monitors the pressure of the tire. The tire identification code registration system includes a storage manager that stores, in a memory, tire identification codes included in wireless signals received during a predetermined storage period as candidate tire identification codes. A registration unit registers the candidate tire identification codes in the memory as formal tire identification codes after the storage performed by the storage manager when the number of the candidate tire identification codes in the memory is equal to a predetermined storage number.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2013-194217, filed on Sep. 19,2013, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present invention relates to a tire identification code registrationsystem.

A typical tire pressure monitoring system, which includes a transmitterthat transmits a tire pressure signal and a receiver that receives thetire pressure signal, is configured so that the receiver monitors theair pressure of a tire based on the tire pressure signal. Variousmethods have been proposed to register a tire identification code to thereceiver without using a dedicated registration tool other than thetransmitter and the receiver.

For example, Japanese Laid-Open Patent Publication No. 9-210827describes a method for registering four tire identification codesinitially received by a receiver as the tire identification codes of thecorresponding vehicle. Japanese Laid-Open Patent Publication No.2012-236527 describes a system including a receiver and a tire pressuredetector, which is configured to include a sudden pressure decrease bitin a tire pressure signal when the a sudden tire pressure decrease iscarried out. In a registration mode, the receiver receives tireidentification codes and registers the tire identification code thatincludes the sudden pressure decrease bit as the tire identificationcode of the corresponding vehicle.

In the technique of the '827 publication, when another vehicle islocated near the corresponding vehicle during registration of the tireidentification code, the receiver may receive a tire identification codeof the other vehicle before receiving the tire identification code ofthe corresponding vehicle. This may result in erroneous registration ofthe tire identification code. In the technique of the '527 publication,there is a need to carry out a sudden tire pressure decrease during IDregistration. This increases the burden on the person performing theregistration.

SUMMARY

It is an object of the present invention to provide a tireidentification code registration system that can reduce or obviateerroneous registration.

One aspect of the present invention is a tire identification coderegistration system for use with a plurality of tire pressure detectorsand a tire pressure monitoring system (TPMS) receiver. Each of the tirepressure detectors includes a unique tire identification code and isconfigured to be coupled to a tire. Each of the tire pressure detectorsis configured to detect pressure of the corresponding tire and transmita tire pressure signal that includes tire pressure information. Thereceiver is configured to receive the tire pressure signal and monitorthe pressure of the corresponding tire based on the received tirepressure signal. The tire identification code registration systemincludes a storage manager configured to store, in a memory, tireidentification codes included in wireless signals received during apredetermined storage period as candidate tire identification codes. Aregistration unit is is configured to register the candidate tireidentification codes in the memory as formal tire identification codesafter the storage performed by the storage manager when the number ofthe candidate tire identification codes in the memory is equal to apredetermined storage number.

Other aspects and advantages of the present invention will becomeapparent from the following description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best beunderstood by reference to the following description of the presentlypreferred embodiments together with the accompanying drawings in which:

FIG. 1 is a block diagram of a tire identification code registrationsystem in a first embodiment;

FIG. 2 is a schematic diagram illustrating the reception of tireidentification codes during a storage period and the storage of tireidentification codes to the memory;

FIG. 3 is a schematic diagram illustrating the reception of tireidentification codes in a storage period and a deletion period, thestorage of tire identification codes to the memory, and the deletion oftire identification codes in the tire identification code registrationsystem of the first embodiment;

FIG. 4 is a block diagram of a tire identification code registrationsystem in a second embodiment; and

FIG. 5 is a schematic diagram illustrating the reception of tireidentification codes in a storage period and a deletion period, thestorage of tire identification codes to the memory, and the deletion oftire identification codes in the tire identification code registrationsystem of the second embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS First Embodiment

A first embodiment of a tire identification code registration systemwill now be described with reference to the drawings.

Referring to FIG. 1, a vehicle 1 includes a tire pressure monitoringsystem (TPMS) 3 that monitors the tire pressure and the like of tires 2a to 2 e. The tire pressure monitoring system 3 of the first embodimentincludes transmitters, or tire pressure detectors 4 (4 a to 4 e), and areceiver 13. The tire pressure detectors 4 a to 4 e are respectivelyarranged in the tires 2 a to 2 e. The receiver 13 is capable ofperforming wireless communication with the tire pressure detectors 4 ato 4 e. Each tire pressure detector 4 may be integrated with a tirevalve. Each of the tire pressure detectors 4 a to 4 e detects the tirepressure and transmits a tire pressure signal Stp, which includes tirepressure information. In the illustrated example, the vehicle 1 travelson the tires 2 a to 2 d and stores the tire 2 e as a spare tire.

Each of the tire pressure detectors 4 a to 4 e is provided with acontroller 6 that includes a memory 7, a rotation determination unit 12a, and a transmission control unit 12 b. The memory 7 of the controller6 stores a unique tire identification code (valve identification code).The tire identification code may be referred to as the tire ID. In theillustrated example, the controller 6 is connected to a pressure sensor8, which detects the tire pressure, a temperature sensor 9, whichdetects the tire temperature, and an acceleration sensor 10, whichdetects rotation of the corresponding tire 2. The controller 6 isconnected to a transmission antenna 11, which is capable of transmittingradio waves on the ultrahigh frequency (UHF) band.

Each tire pressure detector 4 periodically transmits a tire pressuresignal Stp in controlled cycles. The tire pressure detectors 4 a to 4 emay transmit the tire pressure signal Stp in the same cycle or indifferent cycles. In one example, the tire pressure detectors 4 a to 4 etransmit the tire pressure signal Stp at different timings that arerandomly set so that transmissions of the tire pressure signal Stp fromthe tire pressure detectors 4 a to 4 e do not overlap with one another.In several examples, each tire pressure detector 4 transmits the tirepressure signal Stp further frequently when detecting rotation of thecorresponding tire 2 that exceeds a rotation reference value. Whenrotation of the corresponding tire 2 does not exceed the rotationreference value, the tire pressure detector 4 transmits the tirepressure signal Stp less frequently in longer intervals.

The rotation determination unit 12 a of the controller 6 determineswhether or not the corresponding tire is rotating based on, for example,a detection signal of the acceleration sensor 10. The transmissioncontrol unit 12 b switches or changes the transmission cycle of the tirepressure signal Stp in accordance with the determination of the rotationdetermination unit 12 a. In the preferred example, the rotationdetermination unit 12 a includes a rotation determination referencevalue. When the acceleration detected by the acceleration sensor 10 isless than or equal to the rotation determination reference value, therotation determination unit 12 a determines that the tire 2 is notrotating. When the detected acceleration by the acceleration sensor 10is greater than the rotation determination reference value, the rotationdetermination unit 12 a determines that the tire 2 is rotating.Preferably, the rotation determination reference value is set to ensureaccurate determination of rotation of the tire 2. Further, the rotationdetermination reference value may be set as a value that is greater thanzero, taking into consideration the detection accuracy of theacceleration sensor. When the rotation determination unit 12 adetermines that the tire 2 is rotating, the transmission control unit 12b controls the transmission cycle so that the tire pressure signal Stpis transmitted in first time intervals (e.g., one minute intervals).When the rotation determination unit 12 a determines that the tire 2 isnot rotating, the transmission control unit 12 b controls thetransmission cycle so that the tire pressure signal Stp is transmittedin second time intervals (e.g., two minute intervals), which are longerthan the first time intervals.

Each tire pressure detector 4 transmits a tire pressure signal Stp thatincludes a plurality of frames when the corresponding tire 2 is rotatingand transmits a tire pressure signal Stp that includes only a singleframe when the tire 2 is not rotating. Each frame includes a tire ID andtire pressure information regardless of rotation of the tire 2.

The TPMS receiver 13 may be installed on a vehicle body 5. The receiver13 is configured to receive the tire pressure signals Stp from the tirepressure detectors 4 a to 4 e and monitor the tire pressure of each ofthe tires 2 a to 2 e. The receiver 13 includes a tire pressuremonitoring system electronic control unit (TPMS ECU) 14 and a receptionantenna 15, which is capable of receiving radio waves on the UHF band.The TPMS ECU 14 is provided with a memory 16, which may include anonvolatile region 16 a and a volatile region 16 b. Once tire IDregistration is completed, the tire IDs of the tires 2 a to 2 e arestored (registered) in the nonvolatile region 16 a in a nonvolatilemanner. The tire IDs are temporarily held in the volatile region 16 bduring the tire ID registration. In several examples, the nonvolatileregion 16 a and the volatile region 16 b may be a nonvolatile memoryelement and a volatile memory element. The term “tire ID registration”may refer to the nonvolatile storage of the tire IDs. The receiver 13may be connected to a display 17 set on, for example, an instrumentpanel in the vehicle 1.

When the receiver 13 receives the tire pressure signal Stp from each ofthe tire pressure detectors 4 a to 4 e, the receiver 13 verifies thetire ID in the tire pressure signal Stp with the tire ID registered tothe nonvolatile region 16 a of the memory 16. When the tire ID isverified, the receiver 13 checks the tire pressure information that isincluded in the tire pressure signal Stp. When the measured pressure inthe tire pressure information is less than or equal to a low pressuredetermination reference value, the receiver 13 indicates a tire pressurewarning on the display 17. The receiver 13 may check the tire pressurewhenever receiving the tire pressure signal Stp.

Tire ID Registration

The tire pressure monitoring system 3 includes a tire ID registrationsystem 18 that registers the tire IDs of the tires 2 a to 2 e to thereceiver 13. In the first embodiment, the tire ID registration system 18temporarily stores the tire ID included in a tire pressure signalreceived during a predetermined storage period TM as a candidate tire IDin the memory 16. After the predetermined storage period TM ends, whenthe number of candidate tire IDs in the memory 16 is equal to apredetermined storage number, the tire ID registration system 18registers the candidate IDs in the memory 16 as formal tire IDs, or IDsof the corresponding vehicle. The number of candidate tire IDs indicatesthe number of different unique tire IDs. For example, when the sameunique tire ID is received a number of times during the predeterminedstorage period TM, the unique tire ID is stored as a single candidatetire ID in the memory 16. The predetermined storage number may be, forexample, the number of tires 2 of the vehicle 1. In the firstembodiment, the storage number may be five (2 a to 2 e) including thespare tire 2 e.

In one example, the TPMS ECU 14 includes an operation mode manager 21,which switches operation modes (e.g., normal mode and registration mode)of the receiver 13, a travel determination unit 22, which determineswhether or not the vehicle 1 is travelling, and an announcement unit 23,which announces the ID registration status through the display 17. Inthe illustrated example, the TPMS ECU 14 is connected to an input devicesuch as a mode switching button 24. When manually operated, the modeswitching button 24 outputs a mode switching request to switch the modeof the receiver 13.

In one example, the operation mode manager 21 switches the receiver 13between a pressure monitoring mode and a registration mode in accordancewith a mode switching request from an input device such as the modeswitching button 24. In the pressure monitoring mode, the receiver 13monitors the tire pressure based on the tire pressure signal Stptransmitted from each tire pressure detector 4. In the registrationmode, the receiver 13 registers tire IDs as will be described later. Thetravel determination unit 22 obtains, for example, a detected vehiclespeed (speed information) from a meter ECU, a vehicle speed sensor, orthe like. When the detected vehicle speed is greater than or equal to atravel determination reference value, the receiver 13 determines thatthe vehicle 1 is travelling. When the detected vehicle speed is lessthan the travel determination reference value, the receiver 13determines that the vehicle 1 is not travelling. Taking intoconsideration the accuracy of the detected vehicle speed, the traveldetermination reference value may be, for example, approximately 5 to 30km/h. When the receiver 13 switches to the registration mode, theannouncement unit 23 shows a sign on the display 17 to announce that thereceiver 13 is in the registration mode. After the ID registration iscompleted, the announcement unit 23 eliminates the sign from the display17. When the registration mode is terminated but the ID registration isincomplete, the announcement unit 23 shows a sign on the display 17 toannounce that ID registration has not been completed. This allows thetire ID registration system 18 to present the tire ID registrationstatus.

The TPMS ECU 14 includes a storage manager 25, which temporarily storestire IDs in the volatile region 16 b of the memory 16, a deletion unit26, which deletes tire IDs from the volatile region 16 b, and aregistration unit 27, which registers the candidate tire IDs in thevolatile region 16 b as formal tire IDs.

In several examples, if the travel determination unit 22 determines thatthe vehicle 1 is travelling when the receiver 13 is in the registrationmode, the storage manager 25 stores, in the volatile region 16 b of thememory 16, only tire IDs that are included in wireless signals (e.g.,tire pressure signal Stp) received during the predetermined storageperiod TM (storage process). The storage manager 25 does not store, inthe memory 16, the tire ID included in a tire pressure signal Stpreceived when the vehicle is not travelling. Each tire ID stored in thevolatile region 16 b may be referred to as a candidate tire ID. Thestorage manager 25 does not store, in the memory 16, the tire IDincluded in a tire pressure signal Stp received during a predetermineddeletion period TD.

In several examples, if the storage manager 25 determines that thevehicle 1 is not travelling before the predetermined storage period TMends from when determining that the receiver 13 is in the registrationmode while the vehicle 1 is travelling, the storage manager 25temporarily stops measuring time. When determining that the vehicle 1 istravelling again, the storage manager 25 resumes the time measurement.For example, even when the vehicle 1 stops during the predeterminedstorage period TM, the storage manager 25 ends the storage process ifthe total time period during which the vehicle 1 is travelling exceedsthe predetermined storage period TM. Further, the predetermined storageperiod TM is set to have a duration allowing the tire pressure signalStp to be transmitted a number of times from a tire pressure detector 4even when the tire pressure detector 4 transmits the tire pressuresignal Stp in time intervals corresponding to the second time interval(time interval when tire is not rotating).

When the number of candidate tire IDs in the volatile region 16 b isgreater than the predetermined storage number, the deletion unit 26 isconfigured to delete the candidate tire IDs in accordance with adeletion condition. In a preferred example, when the number of candidatetire IDs in the volatile region 16 b is greater than the predeterminedstorage number, the deletion unit 26 deletes each tire ID that is notincluded in a tire pressure signal Stp received when the traveldetermination unit 22 determines that the vehicle 1 is travelling whilethe receiver 13 is in the registration mode during the predetermineddeletion period TD (deletion process). In other words, among thecandidate tire IDs in the volatile region 16 b, the deletion unit 26deletes only the tire IDs that are not included in tire pressure signalsreceived when the vehicle 1 is travelling. After performing the deletionprocess once, if the number of tire IDs remaining in the volatile region16 b of the memory 16 is still greater than the predetermined storagenumber, the deletion unit 26 repeats the deletion process.

In several examples, in the same manner as the storage manager 25, ifthe deletion unit 26 determines that the vehicle 1 is not travellingbefore the predetermined deletion period TD ends from when determiningthat the receiver 13 is in the registration mode while the vehicle 1 istravelling, the storage manager 25 temporarily stops measuring time.Then, when determining that the vehicle 1 is travelling again, thestorage manager 25 resumes the time measurement. For example, even whenthe vehicle 1 stops during the predetermined deletion period TD, thestorage manager 25 ends the deletion process if the total time periodduring which the vehicle 1 is travelling exceeds the predetermineddeletion period TD. Further, in the same manner as the predeterminedstorage period TM, the predetermined deletion period TD is set to have aduration allowing the tire pressure signal Stp to be transmitted anumber of times from a tire pressure detector 4 even when the tirepressure detector 4 transmits the tire pressure signal Stp in timeintervals corresponding to the second time interval. The predeterminedstorage period TM and the predetermined deletion period TD may have thesame length or different lengths.

The TPMS ECU 14 includes a registration termination unit 28 thatswitches the operation mode of the receiver 13 to a non-registrationmode to terminate the registration mode even when the registrationprocess performed by the registration unit 27 is incomplete. Forexample, when the number of candidate tire IDs in the volatile region 16b of the memory 16 continues to be unequal to the predetermined storagenumber over a predetermined registration period or longer, the operationmode of the receiver 13 is switched to the non-registration mode. Thepredetermined registration period has a duration including thepredetermined storage period TM and a predetermined number of thepredetermined deletion periods TD. Further, after the storage process isperformed or the deletion process is performed, when the number ofcandidate tire IDs in the volatile region 16 b of the memory 16 becomesless than the predetermined storage number, the registration terminationunit 28 switches the operation mode of the receiver 13 to thenon-registration mode. If the receiver 13 is switched to thenon-registration mode when the registration unit 27 has not completedthe registration process, the tire IDs obtained before switching fromthe registration mode remains registered to the receiver 13.

The tire ID registration performed by the tire ID registration system 18of the present embodiment will now be described. In the descriptionhereafter, the tire IDs of the corresponding vehicle 1 will be referredto as “ID1” to “ID5”, and the tire IDs of other vehicles will bereferred to as “ID6” to “ID20”.

When registering tire IDs to the receiver 13, the person performing theregistration, namely, the registrant, first switches the receiver 13 tothe registration mode by operating the mode switching button 24 and thendrives the vehicle 1.

FIG. 2 illustrates a typical example when another vehicle is not locatednear the receiver 13. In this example, during the predetermined storageperiod TM, the receiver 13 receives “ID1” three times, “ID2” and “ID3”four times, “ID4” three times, and “ID5” two times but does not receive“ID6” to “ID20” of the other vehicles. In this case, the storage manager25 stores “ID1” to “ID5” as candidate tire IDs in the memory 16. Sincethe number candidate tire IDs is the same as the predetermined storagenumber (five), the deletion unit 26 does not perform the deletionprocess, and the registration unit 27 registers “ID1” to “ID5” as theformal tire IDs of the corresponding vehicle 1 to the receiver 13. Afterthe registration is completed, the operation mode manager 21 switchesthe operation mode of the receiver 13 to the non-registration mode.

FIG. 3 illustrates a typical example when one or more other vehicles arelocated near the receiver 13. In this example, during the predeterminedstorage period TM, the receiver 13 receives “ID1” to “ID5” in the samemanner as in FIG. 2 and further receives “ID6” six times, each of “ID7”,“ID9”, and “ID11” two times, each of “ID14” and “ID17” once, and “ID19”twice. In this case, the storage manager 25 stores “ID1” to “ID7”,“ID9”, “ID11”, “ID14”, “ID17”, and “ID19” as candidate tire IDs in thememory 16. The number of candidate tire IDs stored in the volatileregion 16 b of the memory 16 is twelve and greater than thepredetermined storage number (five). Thus, the deletion process isperformed next.

In the example illustrated in FIG. 3, after the predetermined storageperiod TM and during the predetermined deletion period TD, the receiver13 receives “ID1” three times, “ID2” and “ID3” twice, “ID4” three times,and each of “ID5”, “ID6”, “ID9”, and “ID13” once. In this case, thedeletion unit 26 does not receive “ID7”, “ID11”, “ID14”, “ID17”, and“ID19” during the predetermined deletion period TD and deletes these IDsfrom the candidate tire IDs in the volatile region 16 b of the memory16. In the illustrated example, the tire IDs received during thepredetermined deletion period TD includes “ID13”, which is not includedin the candidate tire IDs stored in the volatile region 16 b of thememory 16. The storage manager 25 stores only the tire IDs receivedduring the predetermined storage period TM. Thus, the storage manager 25does not store “ID13” in the volatile region 16 b. The number ofcandidate tire IDs in the memory 16 when the first deletion process endsis seven and greater than the predetermined storage number. Thus, thedeletion unit 26 repeats the deletion process.

In the example illustrated in FIG. 3, in the second predetermineddeletion period TD, the receiver 13 receives “ID1” twice, “ID2” threetimes, “ID3” and “ID4” twice, and “ID5” and “ID19” once. In this case,the deletion unit 26 does not receive “ID6” and “ID9” during the secondpredetermined deletion period TD and deletes these IDs from thecandidate tire IDs in the volatile region 16 b of the memory 16. In theexample of FIG. 3, the tire IDs received during the second predetermineddeletion period TD includes “ID19”, which is not included in thecandidate tire IDs stored in the volatile region 16 b of the memory 16.The storage manager 25 stores only the tire IDs received during thepredetermined storage period TM. Thus, the storage manager 25 does notstore “ID19” in the memory 16. The number of candidate tire IDs in thememory 16 when the second deletion process ends is five and equal to thepredetermined storage number of five. Thus, the registration unit 27performs the registration process and registers “ID1” to “ID5” as theformal tire IDs of the corresponding vehicle 1. After the registrationis completed, the operation mode manager 21 switches the operation modeof the receiver 13 to the non-registration mode.

In several examples, if the number of the candidate tire IDs in thememory 16 continuously remains greater than the predetermined storagenumber over the predetermined registration period or longer, theoperation mode manager 21 switches the operation mode of the receiver 13to the non-registration mode without completing the registrationprocess. Further, when the number of candidate tire IDs in the memory 16after the storage process or the deletion process becomes less than thepredetermined storage number, the operation mode manager 21 switches theoperation mode of the receiver 13 to the non-registration mode withoutcompleting the registration process.

The advantages of the first embodiment will now be described.

(1) The storage manager 25 stores the tire ID included in each tirepressure signal Stp received during the predetermined storage period TMas a candidate tire identification code in the memory 16. If the numberof candidate tire IDs in the memory 16 is equal to the predeterminedstorage number, the registration unit 27 registers the candidate tireidentification codes in the memory 16 as formal tire identificationcodes. This configuration allows the registrant to easily register tireIDs and eliminates the need to carry out a suddenly tire pressuredecrease. As long as the number of tire IDs stored in the predeterminedstorage period TM differs from the predetermined storage number, thestorage manager 25 does not register the candidate tire identificationcodes in the memory 16 as the formal tire identification codes. Thus,even if tire IDs of other vehicles near the receiver 13 are firstreceived during ID registration, erroneous registration of the tire IDsof other vehicles is obviated or reduced.

(2) The storage manager 25 stores the tire ID included in each tirepressure signal Stp received when the vehicle 1 is travelling in thevolatile region 16 b of the memory 16 and does not store the tire IDincluded in each tire pressure signal Stp received when the vehicle 1 isnot travelling. During a non-travelling period, the receiver 13 may becontinuously located near another vehicle over a long period. Thisincreases opportunities in which the receiver 13 may receive the tireidentification code of the other vehicle. Thus, the memory 16 does notstore a tire identification code that is included in a tire pressuresignal Stp received during a non-travelling period. This obviates orreduces the storage of the tire identification code of another vehiclein the memory 16.

(3) After the storage manager 25 performs the storage process, if thenumber of candidate tire IDs in the volatile region 16 b of the memory16 is greater than the predetermined storage number, the deletion unit26 deletes the tire ID of each tire pressure signal Stp that is notreceived during the predetermined deletion period TD from the candidatetire IDs in the volatile region 16 b.

Under a normal situation, a tire pressure signal Stp including a tire IDof the corresponding vehicle 1 can be received as long as, for example,the tire pressure detector 4 does not become defective. However, a tirepressure signal Stp including a tire ID of another vehicle can bereceived only when the other vehicle is located near the correspondingvehicle 1. Even when a tire pressure signal Stp including a tire ID ofanother vehicle is received during the predetermined storage period TM,there is a high probability that such a tire pressure signal Stp cannotbe continuously received after the predetermined storage period TM.Thus, by deleting the tire ID that was not received during thepredetermined deletion period TD from the candidate tire IDs in thememory 16, the tire ID of another vehicle may be eliminated from thecandidate tire IDs. This readily decreases the number of candidate tireIDs in the volatile region 16 b to the predetermined storage number andallows for selective registration of the tire IDs of the correspondingvehicle 1.

(4) The deletion unit 26 repeats the tire ID deletion until the numberof candidate tire IDs in the memory 16 becomes equal to thepredetermined storage number. The number of candidate tire IDs in thevolatile region 16 b of the memory 16 readily decreases to thepredetermined storage number. This allows for selective registration ofthe tire IDs of the corresponding vehicle 1.

(5) The storage manager 25 does not store, in the volatile region 16 bof the memory 16, the tire ID included in each tire pressure signal Stpreceived during the predetermined deletion period TD. After performingthe storage process, new tire IDs are not stored in the volatile region16 b. The number of candidate tire IDs in the volatile region 16 b ofthe memory 16 readily decreases to the predetermined storage number.This allows for selective registration of the tire IDs of thecorresponding vehicle 1.

(6) The predetermined storage period TM and/or the predetermineddeletion period TD are set to have a duration allowing the tire pressuresignal Stp to be transmitted a number of times from each tire pressuredetector 4. This increases the probability of the receiver 13 receivingtire pressure signals Stp including the tires ID of the correspondingvehicle 1.

(7) When a situation in which the number of candidate tire IDs in thevolatile region 16 b of the memory 16 is unequal to the predeterminedstorage number continues over the predetermined registration period orlonger, the registration termination unit 28 switches the receiver 13 tothe non-registration mode.

When the registration process is not completed even when a long periodelapses from when the receiver 13 enters the registration mode, forexample, the corresponding vehicle 1 may be located in an environment inwhich tire pressure signals Stp including the tire IDs of other vehiclesare easily received. Thus, when a situation in which the number ofcandidate tire IDs in the volatile region 16 b of the memory 16 isunequal to the predetermined registration period continues over apredetermined period or longer like in the configuration describedabove, the receiver 13 is switched to the non-registration mode when theregistration process performed by the registration unit 27 is stillincomplete. Further, an announcement of the incomplete ID registrationis shown on the display 17. This prompts the registrant to perform theID registration again.

(8) When the number of candidate tire IDs in the volatile region 16 b ofthe memory 16 is less than the predetermined storage number, theregistration termination unit 28 switches the receiver 13 to thenon-registration mode and announces on the display 17 that IDregistration is incomplete. Thus, the registrant is prompted to performID registration again at an early stage.

(9) The transmission control unit 12 b of each tire pressure detector 4transmits the tire pressure signal Stp further frequently when thecorresponding tire 2 is rotating than when the tire 2 is not rotating.Further, when the receiver 13 is in the registration mode and thevehicle 1 is travelling, the storage manager 25 stores, in the memory16, the tire ID included in each tire pressure signal Stp receivedduring the predetermined storage period TM. This increases theprobability of the receiver 13 receiving tire pressure signals Stpincluding the tires ID of the corresponding vehicle 1.

(10) When the receiver 13 is in the registration mode and the vehicle 1is travelling, among the candidate tire IDs in the memory 16, thedeletion unit 26 deletes tire IDs other than the tire IDs included inthe tire pressure signals Stp received during the predetermined deletionperiod TD. When the vehicle 1 is travelling, the time during whichanother vehicle is located nearby is usually short. Thus, in the aboveconfiguration, the tire IDs of other vehicles may be readily deletedfrom the memory.

Second Embodiment

A second embodiment will now be described centering on differences fromthe first embodiment.

As shown in FIG. 4, the TPMS ECU 14 of the present embodiment includes aduration setting unit 29 that changes the duration of the predeterminedstorage period TM and the predetermined deletion period TD in accordancewith the time interval in which each tire pressure detector 4 transmitsthe tire pressure signal Stp. For example, the duration setting unit 29sets the predetermined storage period TM and the predetermined deletionperiod TD to have a duration in which the tire pressure signal Stp istransmitted a number of times from each tire pressure detector 4.Further, if the travel determination unit 22 determines that the vehicle1 is travelling, the duration setting unit 29 shortens the predeterminedstorage period TM and the predetermined deletion period TD as comparedto when the vehicle 1 is determined as not moving.

When the receiver 13 is in the registration mode and the vehicle 1 istravelling, among the tire IDs included in the tire pressure signals Stpreceived during the predetermined storage period TM, the storage manager25 of the present embodiment does not store tire IDs that are presumedas belonging to other vehicles.

Under a normal situation, more tire pressure signals Stp including thetire IDs of the corresponding vehicle 1 can be received than tirepressure signals Stp including the tire IDs of other vehicles. Takingthis into consideration, the storage manager 25 may be configured tostore, among the tire IDs included in the tire pressure signals Stpreceived during the predetermined storage period TM, the tires IDs thatare often received in the volatile region 16 b of the memory 16 and notstore the tire IDs that are seldom received. For example, among the tireIDs included in the tire pressure signal Stp received during thepredetermined storage period TM, the storage manager 25 stores, in thevolatile region 16 b of the memory 16, a selected number of tire IDsranked from above in the number of times received. Further, the storagemanager 25 presumes that tire IDs excluded from selected number of tireIDs are those of other vehicles 1 and does not store such tire IDs inthe volatile region 16 b of the memory 16. The predetermined selectednumber is greater than the predetermined storage number and may be, forexample, ten. The number of times received may be replaced by the numberof received frames.

When performing ID registration without using a registration tool, thetire pressure signal Stp transmitted from the tire pressure detector 4of each tire of the corresponding vehicle 1 does not include triggerinformation (trigger bit having a high level), which would indicate thatthe tire pressure signal Stp has been transmitted in response to atrigger signal transmitted from a trigger transmitter (not shown) suchas an initiator. Taking this into consideration, among the tire IDsincluded in the tire pressure signals Stp received during thepredetermined storage period TM, the storage manager 25 presumes thatthe tire ID in each tire pressure signal Stp including a trigger bit isthat of another vehicle and does not store that tire ID in the volatileregion 16 b of the memory 16.

The tire ID registration performed by the tire ID registration system 18of the present embodiment will now be described. In this case, “ID11”includes a trigger bit having a high level.

In the example shown in FIG. 5, “ID1” to “ID20” are received during thepredetermined storage period TM in the same manner as the example shownin FIG. 3. When taking into consideration the number of times each tireID is received, the tires IDs included in the selected number in orderfrom the ones often received are “ID1” to “ID7”, “ID9”, “ID11”, and“ID19”. In this case, “ID14” and “ID17” are each received only once andexcluded from the selected number. The storage manager 25 stores, in thevolatile region 16 b of the memory 16, the tires IDs excluding “ID14”and “ID17”, which are not included in the selected number, and “ID11”,which includes the high-level trigger bit.

In the example shown in FIG. 5, the volatile region 16 b of the memory16 stores nine tire IDs, the number of which is greater than thepredetermined storage number of five. Thus, the registration process isnot performed and the deletion process is performed. When the number ofcandidate tire IDs in the volatile region 16 b becomes equal to thepredetermined storage number in the same manner as the first embodiment,the registration unit 27 performs the registration process.

In addition to advantages (1) to (10) of the first embodiment, thesecond embodiment has the advantages described below.

(11) The duration setting unit 29 sets the duration of the predeterminedstorage period TM and/or the predetermined deletion period TD to allowthe tire pressure signal Stp to be transmitted a number of times fromeach tire pressure detector 4. Further, when determining that thevehicle 1 is travelling, the duration setting unit 29 sets thepredetermined storage period TM and/or the predetermined deletion periodTD to be shorter than when the vehicle is not travelling. This increasesthe probability of the receiver 13 receiving tire pressure signals Stpincluding the tires ID of the corresponding vehicle 1 and shortens thetime used for ID registration.

(12) Among the tire IDs included in the tire pressure signal Stpreceived during the predetermined storage period TM, the storage manager25 does not store tire IDs that are presumed to belong to othervehicles. This decreases the number of candidate tire IDs in thevolatile region 16 b of the memory 16 after the storage process. Thus,for example, the memory 16 may be more compact.

It should be apparent to those skilled in the art that the presentinvention may be embodied in many other specific forms without departingfrom the spirit or scope of the invention. Particularly, it should beunderstood that the present invention may be embodied in the followingforms.

The receiver 13 or the TPMS ECU 14 in the second embodiment may beconfigured to presume that a tire ID belongs to another vehicle from thenumber of times the tire ID is received during the predetermined storageperiod. For example, when each tire pressure detector 4 transmits thetire pressure signal Stp in fixed cycles, there is an upper limit to thenumber of times the tire pressure signal Stp is transmitted during thepredetermined storage period T is determined. Thus, the receiver 13 orthe TPMS ECU 14 may be configured to presume that a tire ID received fora number of times that is greater than the predetermined upper limitbelongs to another vehicle. Further, the receiver 13 or the TPMS ECU 14in the second embodiment may be configured to presume that a tire IDbelongs to another vehicle when the tire ID is included in a tirepressure signal Stp that is provided with a trigger bit having a highlevel. For example, the receiver 13 of the TPMS ECU 14 may be configuredto presume that a tire ID belongs to another vehicle when the tire ID isincluded in a wireless signal received in cycles that differ from thefixed cycles in which each tire pressure detector 4 transmits the tirepressure signal Stp.

The receiver 13 or the TPMS ECU 14 of the first embodiment may includethe duration setting unit 29 of the second embodiment.

The receiver 13 or the TPMS ECU 14 of the first embodiment may beconfigured not to store, among the tire IDs included in the tirepressure signals Stp received during the predetermined storage period,the tire IDs that are presumed to belong to other vehicles.

The receiver 13 or the TPMS ECU 14 in each of the above embodiments maybe configured to store, in the memory 16, the tire ID included in eachtire pressure signal received during the predetermined storage period TMregardless of whether or not the vehicle 1 is travelling. For example,regardless of whether or not the vehicle 1 is travelling, the receiver13 or the TPMS ECU 14 may measure the predetermined storage period TMand/or the predetermined deletion period TD regardless of whether or notthe vehicle 1 is travelling.

In each of the above embodiments, when the storage process is performed,if determined that the vehicle 1 is not travelling before thepredetermined storage period TM elapses from when determined that thevehicle 1 is travelling, the measurement of the storage period TM istemporarily stopped, and the measurement is resumed when determined thatthe vehicle 1 is travelling again. Instead, if determined that thevehicle 1 is not travelling before the predetermined storage period TMelapses from when determined that the vehicle 1 is travelling, forexample, the registration mode may be terminated and the receiver 13 maybe returned to the original mode. In the same manner, when the deletionprocess is performed, if determined that the vehicle 1 is not travellingbefore the predetermined deletion period TD elapses from when determinedthat the vehicle 1 is travelling, for example, the registration mode maybe terminated and the receiver 13 may be returned to the original mode.

In each of the above embodiments, the operation mode manager 21 may keepthe receiver 13 in the registration mode so that the receiver 13 is notswitched to the non-registration mode even when a situation in which thenumber of candidate tire IDs in the volatile region 16 b of the memory16 is unequal to the predetermined storage number continues over thepredetermined registration period or longer. Further, the operation modemanager 21 may keep the receiver 13 in the registration mode so that thereceiver 13 is not switched to the non-registration mode even when thenumber of candidate IDs in the memory 16 becomes less than thepredetermined storage number. The non-registration mode may be a modethe receiver 13 enters before switching to the registration mode. Forexample, the non-registration mode may be a specific mode such as apressure monitoring mode.

In each of the above embodiments, the deletion unit 26 repeats thedeletion process. Instead, the deletion process may be performed onlyonce. In this case, as long as the number of candidate IDs in the memory16 after the deletion process is performed is unequal to thepredetermined storage number, the operation mode manager 21 terminatesthe registration mode and switches to the original mode.

In each of the above embodiments, the deletion unit 26 may be omittedfrom the receiver 13.

In each of the above embodiments, the predetermined storage period TMmay be set as a period in which the tire pressure detector 4 transmitsthe tire pressure signal Stp only once. In the same manner, thepredetermined deletion period TD may be set as a period in which thetire pressure detector 4 transmits the tire pressure signal Stp onlyonce.

In each of the above embodiments, the time interval in which each tirepressure detector 4 transmits the tire pressure signal Stp when thecorresponding tire 2 rotates does not have to be shorter than that whenthe tire 2 does not rotate. For example, the time interval when the tire2 rotates may be equal to the time interval when the tire 2 does notrotate.

In each of the above embodiments, when a tire ID that is not stored inthe volatile region 16 b of the memory 16 exists among the tire IDsincluded in the tire pressure signals Stop received during thepredetermined deletion period TD while the deletion unit 26 performs adeletion process, the storage manager 25 may store that tire ID in thevolatile region 16 b. In such a configuration, for example, in FIG. 3,the volatile region 16 b of the memory 16 stores “ID13” after the firstpredetermined deletion period TD elapses.

In a configuration in which the storage manager 25 stores, in thevolatile region 16 b, the tire IDs included in tire pressure signals Stpreceived during the predetermined deletion period, among the tire IDsincluded in the tire pressure signals Stp received during thepredetermined deletion period TD, when a tire ID that is not stored inthe volatile region 16 b is the same as a tire ID that has been deletedby the deletion unit 26, it is preferred that such an ID not be storedin the volatile region 16 b. In such a configuration, for example, asshown in FIG. 3, after the second predetermined deletion period TDelapses, “ID19” is not stored in the volatile region 16 b of the memory16.

Further, in a configuration that stores, in the volatile region 16 b,the tire IDs included in the tire pressure signals Stp that the storagemanager 25 receives during the predetermined deletion period TD, when atire ID included in a tire pressure signal Stp received during thepredetermined deletion period TD is presumed to be a tire ID of anothervehicle, that tire ID does not have to be stored.

In each of the above embodiments, the travel determination unit 22determines whether or not the vehicle 1 is travelling based on the speeddetection value (vehicle speed information) obtained from the meter ECU.Instead, each tire pressure detector 4 may be configured to transmit atire pressure signal Stp that includes travel information indicatingwhether or not the tire 2 is rotating, and the travel determination unit22 may determine that the vehicle 1 is travelling when receiving travelinformation indicating that the tire 2 is rotating.

In each of the above embodiments, in lieu of or in addition to thedisplay 17, the announcement unit 23 may include a visual, audio, ortactile device, such as a hazard lamp, a buzzer, or a speaker, toannounce the registration situation of the tire IDs.

If the registration mode is terminated before the registration unit 27completes the registration process, the announcement unit 23 does nothave to show a sign indicating that ID registration is incomplete anddoes not have to announce that the registration mode has been terminatedin an abnormal manner. In this case, the announcement unit 23 mayannounce that, for example, tire pressure signals Stp including tire IDsregistered in the receiver 13 cannot be temporarily received. Thisconfiguration allows the registrant to recognize that the registrationmode has been terminated although the registration process isincomplete.

The input device that switches the operation mode of the receiver 13 maybe changed. For example, the operation mode of the receiver 13 may beswitched when the brake pedal is depressed a predetermined number oftimes. Further, the receiver 13 may be switched to the registration modewhenever the ignition switch is activated.

The tire pressure signal Stp may include a single frame when thecorresponding tire 2 rotates. Further, the tire pressure signal Stp mayinclude a plurality of frames when the corresponding tire 2 does notrotate.

It is preferred that a wireless signal including the tire ID be the tirepressure signal Stp. However, other wireless signals that do not includethe tire pressure information may be used as long as the tire ID isincluded. A wireless signal that includes a tire ID may be referred toas a wireless tire ID signal.

In each of the above embodiments, the tire IDs of the tires 2 a to 2 eare written to and saved in the nonvolatile region 16 a of the memory 16irrelevant to the tire location. However, the tire IDs may be writtenand saved in association with the tire locations (right front, leftfront, right rear, left rear, and spare). In this case, when thereceiver 13 determines that the tire pressure of a tire is low, it ispreferred that the location of the low-pressure tire be shown on thedisplay 17.

In each of the above embodiments, the vehicle 1 does not have to includea spare tire (tire 2 e), and the tires 2 that are ID-registered do nothave to include a spare tire.

Each of the components 21 to 23 and 25 to 29 in the receiver 13 may be adedicated circuit. In the same manner, each of the components 12 a and12 b of each tire pressure detector 4 may also be a dedicated circuit.The components 21 to 23 and 25 to 29 of the receiver 13 may be realizedwhen a computer processor of the TPMS ECU 14 executes computer-readableinstructions stored in a non-transitory computer-readable storagemedium. In the same manner, the components 12 a and 12 b of the tirepressure detector 4 may be realized when a computer processor of thecontroller 6 executes computer-readable instructions stored in anon-transitory computer readable storage medium.

By way of example, and not limitation, the non-transitorycomputer-readable media can include RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium which can be used to carry or store desiredprogram code means in the form of computer-executable instructions ordata structures.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. Also, in the above DetailedDescription, various features may be grouped together to streamline thedisclosure. This should not be interpreted as intending that anunclaimed disclosed feature is essential to any claim. Rather, inventivesubject matter may lie in less than all features of a particulardisclosed embodiment. Thus, the following claims are hereby incorporatedinto the Detailed Description, with each claim standing on its own as aseparate embodiment. The scope of the invention should be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1. A tire identification code registration system for use with aplurality of tire pressure detectors and a tire pressure monitoringsystem (TPMS) receiver, each of the tire pressure detectors includes aunique tire identification code and is configured to be coupled to atire, each of the tire pressure detectors is configured to detectpressure of the corresponding tire and transmit a tire pressure signalthat includes tire pressure information, and the receiver is configuredto receive the tire pressure signal and monitor the pressure of thecorresponding tire based on the received tire pressure signal, the tireidentification code registration system comprising: a storage managerconfigured to store, in a memory, tire identification codes included inwireless signals received during a predetermined storage period ascandidate tire identification codes; and a registration unit configuredto register the candidate tire identification codes in the memory asformal tire identification codes after the storage performed by thestorage manager when the number of the candidate tire identificationcodes in the memory is equal to a predetermined storage number.
 2. Thetire identification code registration system according to claim 1,wherein the storage manager is configured to store, in the memory, tireidentification codes included in wireless signals received during aperiod in which a detected vehicle speed is greater than a traveldetermination reference value; and the storage manager is configured notto store, in the memory, tire identification codes included in wirelesssignals received during a period in which the detected vehicle speed isless than or equal to the travel determination reference value.
 3. Thetire identification code registration system according to claim 1,further comprising a deletion unit that deletes candidate identificationcodes from the memory when the number of candidate identifications codesin the memory is greater than the predetermined storage number, whereinthe deletion unit is configured to delete each candidate tireidentification code from the memory that is not included in a wirelesssignal received during a predetermined deletion period.
 4. The tireidentification code registration system according to claim 3, whereinwhen the number of the candidate tire identification codes in the memorysubsequent to the deletion is greater than the predetermined storagenumber, the deletion unit repeats the deletion.
 5. The tireidentification code registration system according to claim 3, whereinthe storage manager does not store, in the memory, a tire identificationcode included in a wireless signal received during the predetermineddeletion period.
 6. The tire identification code registration systemaccording to claim 3, wherein the predetermined deletion period has aduration in which each of the tire pressure detectors transmits awireless signal including the tire identification code a number oftimes.
 7. The tire identification code registration system according toclaim 6, further comprising: a transmission control unit installed ineach of the tire pressure detectors, wherein the transmission controlunit detects rotation of the corresponding tire and transmits the tirepressure signal further frequently when the detected tire rotationexceeds a rotation reference value; and a duration setting unitinstalled in the receiver, wherein the duration setting unit changes theduration of the predetermined deletion period in accordance with adetected vehicle speed.
 8. The tire identification code registrationsystem according to claim 1, wherein the predetermined storage periodhas a duration in which each of the tire pressure detectors transmits awireless signal including the tire identification code a number oftimes.
 9. The tire identification code registration system according toclaim 8, further comprising: a transmission control unit installed ineach of the tire pressure detectors, wherein the transmission controlunit detects rotation of the corresponding tire and transmits the tirepressure signal further frequently when the detected tire rotationexceeds a rotation reference value; and a duration setting unitinstalled in the receiver, wherein the duration setting unit changes theduration of the predetermined storage period in accordance with adetected vehicle speed.
 10. The tire identification code registrationsystem according to claim 1, further comprising a registrationtermination unit installed in the receiver, wherein under a situation inwhich the number of the candidate tire identification codes in thememory continues to be equal to the predetermined storage number over apredetermined storage period or longer, the registration terminationunit switches an operation mode of the receiver from a tireidentification code registration mode to a non-registration mode. 11.The tire identification code registration system according to claim 1,further comprising a registration termination unit installed in thereceiver, wherein under a situation in which the number of the candidatetire identification codes in the memory is less than the predeterminedstorage number, the registration termination unit switches an operationmode of the receiver from a tire identification code registration modeto a non-registration mode.
 12. The tire identification coderegistration system according to claim 1, wherein the storage managerincludes a presumption condition and is configured to use thepresumption condition to presume that a wireless signal received duringthe predetermined storage period was transmitted from another vehicle,and among the tire identification codes included in wireless signalsreceived during the predetermined storage period, the storage manager isconfigured not to store a tire identification code presumed as havingbeen included in a wireless signal transmitted from another vehicle. 13.A controller for a tire pressure monitoring system, the controllercomprising: a volatile memory element; a nonvolatile memory element; anda computer processor coupled to the volatile memory element and thenonvolatile memory element and configured to: store, in the volatilememory element, a tire identification code included in each tirepressure signal received during a predetermined storage period as acandidate tire identification code, register, to the nonvolatile memoryelement, each candidate tire identification code as a formal tireidentification code if the number of the candidate tire identificationcodes in the volatile memory element when the predetermined storageperiod ends is equal to a predetermined storage number; and delete acandidate tire identification code that meets a deletion condition fromthe volatile memory element if the number of the candidate tireidentification codes in the volatile memory element when thepredetermined storage period ends is greater than a predeterminedstorage number.
 14. A tire pressure monitoring system comprising: a tirepressure detector including a unique tire identification code, whereinthe tire pressure detector is coupled to a tire and configured to detectpressure of the tire and transmit a tire pressure signal that includestire pressure information; a receiver configured to receive the tirepressure signal and monitor the pressure of the corresponding tire basedon the tire pressure signal; and the controller according to claim 13,wherein the controller is installed in or coupled to the receiver.
 15. Anon-transitory computer-readable storage medium having stored thereoninstructions that cause a computer processor to execute a tireidentification code registration method, the instructions comprising:instructions configured to store, in a volatile memory element of a tireidentification code registration system, a tire identification codeincluded in each tire pressure signal received during a predeterminedstorage period as a candidate tire identification code; instructionsconfigured to register, to a nonvolatile memory element of the tireidentification code registration system, each candidate tireidentification code in the volatile memory element as a formal tireidentification code if the number of the candidate tire identificationcodes in the volatile memory element when the predetermined storageperiod ends is equal to a predetermined storage number; and instructionsconfigured to delete a candidate tire identification code that meets adeletion condition from the volatile memory element if the number of thecandidate tire identification codes in the volatile memory when thepredetermined storage period ends is greater than a predeterminedstorage number.